Self-tightening clamp structure

Abstract: A so-called stepless self-tightening clamp structure having a first clamping position (Figure 4) and a second non-clamping position (Figure 3) in which the clamping band (11) is under prestress of its inherent spring characteristics. To latchingly hold the clamp structure in its second position, one end of the clamping band is provided with a tongue-like extension (20) while the other end is provided with two longitudinally extending, slot-like openings (36, 35) following one another by way of a constriction (33), whereby one (36) of the slot-like openings is wider than the tongue-like extension (20) and the other (35) is slightly narrower than the tongue-like extension (20). One (36) of the slot-like openings is thereby offset in the radial direction with respect to at least a part of the other slot-like opening (36). Additionally, to enhance the spring stiffness, the clamping band may be provided with one or more longitudinally extending reinforcing groove.

Description: The present invention relates to a self-tightening clamp structure, and more particularly to a self-tightening reusable clamp structure which provides internal clamping surfaces devoid of steps, offsets or interruptions to assure a completely satisfactory fluid-tight connection. BACKGROUND OF THE INVENTION Self-tightening clamps, i.e., clamps made from spring wire or spring steel band material, which are also referred to in the art as constant-tension clamps, are known as such. In their simplest form, such clamps, which, by their inherent spring characteristics, normally tend to assume their closed clamping position, consist of spring wire with overlapping, outwardly extending ends, and the clamps are opened by forcing the overlapping outwardly extending ends toward one another. Once installed over a hose, the outwardly extending ends are released and the clamp will assume its clamping position. Self-tightening clamps made from band material are also known in the prior art. They usually consist of a tongue-like extension at one end and are preferably provided with a latching device at the other end to latch the clamp in its pre-stressed condition. The thus-opened latched clamps are shipped to the user who will install the open clamps and then release the latching engagement. US-A-4,305,179; US-A-4,425,681; US-A-4,858,279; US-A-4,930,191; US-A-4,930,192; US-A-4,996,749; US-A-5,185,907 and US-A-4,773,129 are representative of prior art self-tightening clamps made from band material, the last-mentioned document disclosing a clamp structure which has the features included in the first part of claim 1. All of these prior art clamps, however, involve an injury danger in use owing to outwardly extending parts thereof, not to mention lack of clamping surfaces devoid of discontinuities, steps or offsets. The clamps described in US-A-5,203,809 represented a significant step in the direction toward greater safety coupled with reliable clamping action over the entire circumference. In particular, the clamp illustrated in Figures 24 to 30 has proved commercially successful. However, apart from being relatively complicated and costly to manufacture, its snap-like release from the latched position into the clamping position occasionally produces some sparking which is unacceptable within the area, for example, of gasoline lines and the like. Sparking danger can be reduced with the use of a lacquer cover layer on the surface of the clamp. However, such lacquer layer again increases the cost of the clamp. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a self-tightening clamp of the type described above which eliminates by simple means the aforementioned short-comings and drawbacks encountered in the prior art. Another object of the present invention resides in a self-tightening clamp which is so constructed and arranged that it can be released from its latched condition most conveniently with a positive guidance by the use of a tool, thereby preventing the snap-like return to the clamping action which might cause sparking. A further object of the present invention resides in a self-tightening clamp of the type described above which is extraordinarily simple in construction and low cost in manufacture. Still another object of the present invention resides in a self-tightening clamp which can be easily opened and closed under positive guidance with the use of the same tool. The underlying problems are solved in accordance with the present invention by the self-tightening clamp structure defined in claim 1; the dependent claims relate to preferred embodiments of the invention. Briefly, the clamp structure hereinafter disclosed has a first clamping position and a second non-clamping position in which the clamping band is under pre-stress of its inherent spring characteristics. To latchingly hold the clamp structure in its second position, one end of the clamping band is provided with a tongue-like extension while the other end is provided with two longitudinally extending, slot-like openings following one another in the longitudinal direction of the clamping band by way of a constriction, with one of the slot-like openings being wider than the tongue-like extension and the other being narrower than the tongue-like extension. One of the slot-like openings is offset in the radial direction with respect to at least a part of the other slot-like opening. Additionally, to enhance the spring characteristics, the clamping band may be provided with a longitudinally extending reinforcing groove. BRIEF DESCRIPTION OF THE DRAWINGS These and other objects, features and advantages of the present invention will become more apparent from the following description which shows, for purposes of illustration only, one embodiment in accordance with the present invention and wherein: Figure 1 is a top plan view on a self-tightening clamp structure in accordance with the present invention; Figure 2 is a side elevational view of the clamp structure of Figure 1; Figure 3 is an axial elevational view of the clamp structures of Figures 1 and 2 in the latched, open condition thereof; Figure 4 is an axial elevational view, similar to Figure 3, but showing the clamp structure in the closed clamping condition in which it clamps a tubular member onto a fixed part; and Figure 5 is a top plan view on the clamp structure shown in Figure 4. DETAILED DESCRIPTION OF THE DRAWINGS Referring now to the drawing wherein like reference numerals are used throughout the various views to designate like parts, the clamp structure generally designated by reference numeral 10 consists of a clamping band 11 which is provided at one end thereof with a tongue-like extension generally designated by reference numeral 20 . The bent-up end portion 21 of the tongue-like extension 20 is provided in its rounded-off end with a tool-engaging notch 22 . The full band width of the clamping band 11 passes over into the tongue-like extension by way of tapering portions 13a and 13b subtending an angle α with respect to the longitudinal direction of the clamping band 11 and rounded-off with a radius of curvature R1 where these tapering portions 13a and 13b pass over into the tongue-like extension 20 . The opposite end portion of the clamp structure generally designated by reference numeral 30 includes a first section 31 connected with a second section 32 by way of a step-like connecting section 33 . The end portion 30 is provided at its rounded-off free end with a tool-engaging notch 34 and, proceeding from that end of the clamping band in the direction toward the tongue-like extension 20 , is provided with a first elongated opening 35 and a second elongated opening 36 in communication by way of a narrow constriction 37 formed by inwardly extending projections 38a and 38b (Figure 5). The tongue-like extension 20 tapers in the end portion 21 in the direction toward its free end, and such taper may be formed by a part of a circular arc of radius R2 on both sides thereof. The clamping band 11 is further provided intermediate the slot-like opening 36 and the tongue-like extension 20 with two openings 14 and 15 which, in the illustrated embodiment, taper toward one another in width. These openings 14 and 15 are provided for ease of handling of the clamp structure. Their number and shapes may be varied depending on the requirements of the clamp structure. The width c , i.e., the dimension in the transverse direction of the clamping band, of the slot-like opening 36 is greater than the width dimension d of the slot-like opening 35 and is also larger than the width b of the tongue-like extension 20 so that the tongue-like extension can slide freely within slot 36 during opening and subsequent release into the clamping position of the clamp structure. On the other hand, the width d of the slot-like opening 35 is preferably somewhat smaller than the width b of the tongue-like extension 20 so that only a part of the tapered end portion 21 can extend through the same. This will facilitate release of the clamp from its latched, open position as will be explained more fully hereinafter. Figure 3 shows the clamp in its open latched position into which it has been forcibly displaced against the inherent springiness of the clamping band material by engagement of a tool as shown, for example, in Figures 31 to 33 of US-A-5,203,809, in tool-engaging notches 22 and 31 . The clamp structure 10 as shown in Figure 3, is held in the open latched position by engagement of the tapering end portion 21 of the tongue-like extension 20 against the rounded end wall 35' of the slot-like opening 35 . To release the clamp structure from its latched, open position in Figure 3, into the unlatched clamping position shown in Figures 4 and 5, the same tool is again engaged in notches 22 and 31 , whereby the free end 21 continues to be positively guided into the clamping position after being released from the latching position by lowering the protruding end portion 21 to pass underneath the constriction 37 . By limiting the extent of projection of the end portion 21 through slot-like opening 35 which is controlled by the width dimensions d and b and by the tapering end portion 21 , release is facilitated by the fact that only the tip of the free end of the tongue-like extension which has to pass underneath the constriction 37 , extends through the slot-like opening 35 . Figure 4 shows the installed clamp structure 10 in which it clampingly holds a tubular member 10 such as a hose or axle boot on a fixed member 50 such as a nipple or rotating member of a CV joint. In a typical example which, however, is non-limitative of the present invention, the dimensions for a clamp structure intended to have an internal diameter in its clamping position of 26.5 mm are as follows: The length of the clamp structure is about 119.7 mm while the width of the clamping band 11 is 10 mm and its thickness is 1.2 mm. The opening 35 has a width d of about 3 mm and a length of about 8 mm. The distance from the rounded-off end of opening 35 to the corresponding end of the clamp structure is about 4 mm. The slot-like opening 36 has a length of about 20 mm and a width c of about 4.5 mm. The opening 14 is spaced with its larger rounded-off end at about 38 mm from the corresponding end of the clamping band and has a length of about 12 mm. The end of the opening 14 with the smaller rounded-off portion is spaced from the end of the opening 15 with smaller rounded-off portion at about 29.2 mm while the opening 15 also has a length of about 12 mm and is spaced with its larger rounded-off end from the free end of the tongue-like portion 20 by about 28.5 mm. The tongue-like portion has a width b of about 4 mm and a length of about 23.3 mm including the tapering surfaces 13a and 13b which subtend an angle α of about 45° with respect to the longitudinal direction of the clamping band. The tapering side surfaces of the end portion 21 are formed by a portion of a circular arc having a radius of curvature of about 2 mm or greater while the tool-engaging notch 22 is formed by a radius of curvature of about 1 mm to a depth of about 0.35 mm. The inclined sides of the openings 14 and 15 intersect at a point halfway between these two openings. The end portion 21 of the tongue-like extension is bent up at an angle about 40° while the step-like portion 33 is bent-up at an angle of about 30° by way of rounded-off transitions having a radius of curvature of about 0.5 mm. In the installed condition, the first outer end section 31 is spaced in the radial direction from the inner overlapped clamping band by a distance s of about 1.2 mm (Figure 4). The length of the bent-up portion 21 is about 5 mm. A radius R1 of about 1 mm is used for the radius of curvature of the tool-engaging notch 22 as also for the transition of the tapering surfaces 13a and 13b into the tongue-like extension while a radius of about 2 mm is used for the radius R2 of the tapering side portions of the tongue-like extension as also for the rounded-off ends of the end portion 30 and the tool-engaging notch 31 . The larger rounded-off ends of openings 14 and 15 are realised with a radius of curvature of about 2.5 mm while the curvature of the smaller ends of the openings 14 and 15 are realised with a radius of curvature of 1.5 mm. It is understood, however, that the dimensions given above are merely for illustrative purposes, but may be varied according to size and use of the clamp structure. Important to the present invention which seeks to obtain a clamp structure devoid of any offset, step or discontinuity along its internal clamping surfaces are the construction of the slot-like openings 35 and 36 as latching means in conjunction with the tongue-like extension 20 as also the use of the step-like portion 33 while the width of the constriction 37 would permit the passage of one jaw of the tool. The clamp structure of this invention is made of very hard material, both from stainless steel as also carbon steel which, if necessary, is hardened and galvanised or externally covered by a lacquer layer to protect against corrosion. A clamp made from stainless steel offers the advantage that the clamps leave the machine in completely finished condition without the need for after-treatment. The clamping band may also be provided with a reinforcing groove extending in the longitudinal direction substantially within the centre to provide a stronger spring stiffness. The reinforcing groove may be interrupted in the area of the openings 35 , 36 , 14 , 15 or may also be provided on both sides of one or more (all) of these openings with a slight overlap with the central reinforcing groove. Though the preferred manner of releasing the clamp structure of this invention from its open latched position is by means of a tool, such as shown in Figures 31 to 33 of US-A-5,203,809, it would also be feasible to release the clamp by the application of a downward directed force on the end portion 21 of the tongue-like extension 20 by the use of an appropriate tool. Furthermore, the basic concept of this invention is also applicable to a clamp structure for fastening a hose or the like which has to be secured from the inside in the radially outward direction, i.e., in which the open latched position has a smaller diameter and the normal clamping position, a larger diameter. It is only necessary in that case to reverse the clamp system so that the clamping surfaces devoid of steps, offsets or discontinuities are now located on the outside, and the position of the openings 35 and 36 is reversed. While only one embodiment of the present invention has been shown and described, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art and encompassed by the scope of the appended claims.

Claims: A self-tightening clamp structure (10) having a first, released position (Figure 4) in which the clamp structure exerts a clamping action and a second position (Figure 3) in which the clamp structure is adapted to be latchingly held against the inherent tightening forces, comprising clamping band means ( 11 ) including a tongue-like extension ( 20 ) at one end thereof having a bent-up end portion ( 21 ), a first slot-like opening ( 36 ) in said clamping band means through which said tongue-like extension ( 20 ) is adapted to slide, and latching means in the other end area of said clamping band means, characterised by an arrangement ( 35, 38a, 38b ) including a passage ( 37 ) in the latching means connected to an area of engagement for said tongue-like extension ( 20 ) in said second position for allowing a tool to stay in continuous engagement with said tongue-like extension ( 20 ) throughout the movement of the clamping band means ( 11 ) from said second to said first position, to prevent sparking during release of the clamp structure from said second position. The clamp structure of claim 1, wherein said arrangement includes a second slot-like opening ( 35 ) in the other end area of said clamping band means ( 11 ) which is separated from said first slot-like opening ( 36 ), and wherein said second slot-like opening ( 35 ) has a smaller dimension in the transverse band direction than the first slot-like opening. The clamp structure of claim 1 or 2, wherein said second slot-like opening ( 35 ) is separated from said first slot-like opening ( 36 ) by constriction means ( 37 ), which has a minimum width in the band transverse direction which is smaller than the width of the tongue-like extension ( 20 ) and its bent-up end portion ( 21 ). The clamp structure of any preceding claim, wherein said tongue-like extension ( 20 ) has a tapered end portion ( 21 ) tapering in the direction toward the free end thereof. The clamp structure of claim 4, wherein the width ( d ) of said second slot-like opening ( 35 ) is smaller than the width ( b ) of the tongue-like extension ( 20 ) by such an amount that the tongue-like extension ( 20 ) can extend into the second slot-like opening ( 35 ) only with its tapered end portion. The clamp structure of claim 4 or 5, wherein the tapered end portion of the tongue-like extension ( 20 ) has a curvilinear configuration which may be part of a circle. The clamp structure of any preceding claim, further comprising notch-like tool-engaging means ( 22, 34 ) in opposite end surfaces of the clamping band means ( 11 ). The clamp structure of any preceding claim, wherein the first and second longitudinally extending slot-like openings ( 36, 35 ) near the other end of the clamping band means are disposed one behind the other in the longitudinal direction of the clamping band means ( 11 ), wherein said two slot-like openings ( 36, 35 ) are of different width in the transverse direction of the clamping band means, and wherein a radially directed offset ( 33 ) is provided in the clamping band means near the other end thereof in such a manner that at least one ( 35 ) of the slot-like openings is radially outwardly displaced with respect to the inner overlapped clamping band means so that the clamp structure provides an uninterrupted clamping action over its entire circumference. The clamp structure of claim 8, wherein the offset portion ( 33 ) also includes a part of the other slot-like opening ( 36 ). The clamp structure of any of claims 3 to 9, wherein said constriction (37) is of such dimension as to preclude the tongue-like extension ( 20 ) to pass from the first slot-like opening ( 36 ) into the second slot-like opening ( 35 ) to thereby provide a latching action for the clamp structure in its second position. The clamp structure of any preceding claim, wherein said first slot-like opening ( 36 ) has a width ( c ) slightly smaller than the width of the tongue-like extension ( 20 ), and wherein said tongue-like extension ( 20 ) has a tapering portion (R2) at the free end thereof whose width varies from the normal width ( b ) of the tongue-like extension ( 20 ) to a width smaller than the width of the first slot-like opening ( 36 ). The clamp structure of any of claims 2 to 11, wherein the clamp structure is reusable, and wherein means ( 37 ) are provided between said two slot-like openings ( 36, 35 ) to hold the clamp structure in its second position against inadvertent release to thereby effectively provide a latching action.

Inventors: OETIKER HANS, OETIKER, HANS
Applicants: OETIKER HANS AG, HANS OETIKER AG
Application year: 1994
Main classification: F16L33
IPC codes: F16L33